"By overwhelming consensus, the scientific community agrees that climate change is real. Greenhouse gases have increased markedly as a result of human activities and now far exceed pre-industrial values."
So says Rajendra Pachauri, Chairman of the Intergovernmental Panel on Climate Change, of Geneva, Switzerland. His remarks bear a warning for each of us and for future generations as well. In a speech to the United Nations Summit on Climate Change in Sept., 2009, Pachauri said warming has already resulted "in an increase in the frequency, intensity and duration of floods, droughts and heat waves."
By year 2020 in Africa, he added, "between 75 and 250 million people are projected to be exposed to water stress due to climate change and in some countries yields from rain-fed agriculture could be reduced by up to 50%." One estimate by the Pentagon puts the number of climate refugees by mid-century at 750-million. What's more, if the planet continues to grow warmer "in the absence of mitigation policies," Pachauri says it could lead to:
# Possible elimination of the Greenland ice sheet and a resulting rise in sea level of about seven meters (23 feet) as well as the possible disappearance of sea ice generally by the latter part of this century. Other authorities note there is far more ice in the Antarctic than in Greenland that is in danger of melting.
# An increase in the frequency of heat waves and heavy precipitation.
# An increase in tropical cyclone intensity.
# A decrease in water resources due to climate change in semi-arid areas such as the western United States, southern Africa and northeastern Brazil.
# An increased risk of extinction for 20 to 30 percent of Earth's species.
Climate authorities say that the rise in sea levels from the melting ice sheets would flood seaboard cities and put hundreds of millions of refugees in motion seeking shelter in northerly climates to find relief from the heat.
Globally, the area affected by drought has been increasing since the 1970s. At the same time, precipitation has increased significantly in eastern parts of North and South America, northern Europe and northern and central Asia, whereas it declined in the Sahel, the Mediterranean, southern Africa and parts of south Asia, Pachauri says.
In recent years, for example, the water level of Lake Powell (it covers portions of Utah and Arizona) has dropped so far that the waterfalls and canyons drowned when Glen Canyon Dam was built are visible again. Meanwhile, in February, 2008, hydrologists reported that at current rates of decline, Lake Mead, behind Hoover Dam, on the Arizona-Nevada border, could be entirely dry in 10 years. In the span from 2000 to 2009, the lake lost half of its water. In 2008, the Scripps Institute of Oceanography issued a paper titled, "When will Lake Mead go dry?" and concluded there was a 50-50 chance that day could dawn as early as 2021. "Today, we are at or beyond the sustainable limit of the Colorado system," concluded the paper's authors. "The alternative to reasoned solutions to this coming water crisis is a major societal and economic disruption in the desert southwest; something that will affect each of us living in the region."
Bill McKibben, author, activist, and founder of 350.org, an organization dedicated to saving the planet from runaway warming caused by carbon dioxide and other emissions, says that the rise in temperatures has been accelerating and that massive, immediate response is urgent. His organization derives its name from c limate scientist James Hansen's contention that any atmospheric concentration of CO2 (carbon dioxide) above 350 parts per million was unsafe, Wikipedia notes. Hansen said, "if humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm, but likely less than that."